Vibrating screen



Sept- 8, 1936- P.- H. TO'EPFER VIBRATING SCREEN 2 Sheets-Sheet 1.

Filed Dec. 15, 1935 Sept. 8, 1936- v P TQEPFER I 2,053,585

VIBRATING SCREEN Filed Dec. 15 1935 2 Shets-Sheet 2 Ig- 5 a Patented Sept. 8, 1936 I f UNITED STATES smear orrlce 1 Claim.

This invention pertains to vibrating screens, and more particularly to screens of the positive actuated type, in which vibratory movement is imparted to the frame of the screening medium 5 by means of an eccentric connection between the screen frame and a power-driven shaft journaled in stationary bearings.

The invention has primarily for its object to improve screens of the foregoing type, and in order that a full appreciation of the invention may be had, the objections encountered in conventional screens now in use will be briefly discussed.

Resiliently supported screens, which receive their vibratory action from over-balanced weights or pulleys, have a number of inherent objections, primary of which is that a resultant vertical, elliptical, vibratory action is imparted to the screen, instead of a circular movement. Consequently, the material has a tendency to flow or slide, rather than roll, as it travels down the screen, thus preventingthe top material from contacting with the screen. Naturally, the elliptical path of movement of the screen becomes elongated as the screen is loaded. Also, the live load exerted upon the resilient supports transmits a secondary vibration'to the screen frame, which is objectionable, and necessitates an extremely heavy structureto overcome the same.

In an endeavor to remedy the foregoing objections, the conventional end support, positive actuated type' of screen was developed, wherein the weight of the screen is intended to be supported entirely by the resilient end supports, and positive circular, vibratory movement is imparted to the screen by eccentrics. While screens of this structure overcome certain objections, in screens actuated by over-balanced weights other serious problems and objections are encountered, in that the eccentric shafts must be accurately counter-balanced, necessitating anadjustable counter-balance, which requires a lengthy and tedious, if not impossible, operation by the trial and error method to effect the proper adjustment. Were it possible to obtain such accurate adjustment, the same would shortly become disorganized upon operation of the screen, which results, in shifting and deterioration of the resilient supports. Furthen the stress set up in the side frame members are such as to require an extremely heavy structure, and these are naturally accentuated when the screen is out of balance. Therefore, the advantages obtained in this type of screen are overcome by the disadvantages, and leave much to be desired in the way of a practical, efficient structure.

It is therefore a main object of the present invention to provide a vibratory screen, having all of the advantages heretofore enumerated, without the attending disadvantages, and this is accomplished by the provision of a positive actuated screen havingsubstantially its entire weightsupported upon the actuating eccentrics, and provided with substantially non-resisting end-holding means to prevent tipping of the screen on the eccentrics.

Incidental to the foregoing, a more specific object resides in the provision of a vibratory screen having substantially its entire weight supported upon the eccentrics, and provided with substantially non-resisting resilient members connecting the ends of the screen and base to prevent tilting of the screen.

Lastly, a more detailed object in connection with the foregoing resides in utilizing substantially non-resistant, resilient straps connecting the ends of the screen and base, and positioned longitudinally with relation to the path of move ment of the screen, each strap being provided with at least one transverse bend.

With the above and other objects in view, which will appear as the description proceeds, the invention resides in the novel construction, combination and arrangement of parts, substantially as hereinafter described, and' more particularly defined by the appended claim, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claim.

In the accompanying drawings is illustrated one complete example of the physical embodiment of the present invention constructed according to the best mode so far devised for the practical application of the principles thereof.

In the drawings:

Figure 1 is an elevation of a screen constructed in accordance with one form of the present invention, parts being broken away and in section to more clearly illustrate the structural features.

Figure 2 is a transverse, fragmentary section taken on the line 2-2 of Figure 1.

Figure 3 is an enlarged fragmentary section taken on the line 33 of Figure 1.

Figure 4 is a plan view of the base, illustrating the end-holding straps attached thereto.

Referring now more particularly to the accompanying drawings, wherein like numerals designate like parts, I indicates generally a base frame comprising longitudinal side members 2 connected:

adjacent their ends by transverse channels 3. When the screen is installed for operation, the base frame I is mounted upon any suitable support, at a desired angle, such as illustrated in Figure 1.

Mounted upon the side channels 2, centrally of their ends, are the journal boxes 4, provided with anti-frictional bearings 5, should the same be desired, and having journaled therein the ends of a transverse shaft 6 provided at opposite sides with eccentric portions 7 journaled in anti-frictional bearings 8 carried by the boxes 9.

Mounted upon the boxes 9 is a frame I0, comprising longitudinal side plates II having angle irons II secured to their outer sides adjacent their lower edges. Attached to the inner faces of the plates II are the angles I2, which carry a screening medium I2 clamped to the angles by brackets I3.

Secured on the transverse shaft 1, preferably between the journal boxes 4 and 9, are the overbalanced ily-wheels I3, which may be constructed in any suitable manner, the over-balanced portion being set opposite to the off-set of the eccentric portions 1 of the shaft 6, so as to counterbalance the weight of the screen throughout its movement imparted by the eccentric mounting of the same on the shaft 6. In the present instance, the fly wheel I3 is shown provided with a separate counter-balance weight I4, secured to the web of the wheel between the hub and outer flange by a rivet I 5, or any other suitable means. This permits the attachment of weights of various sizes, depending upon the weight of the screen employed.

Secured to one end of the shaft 6 is a pulley I6 driven by a belt I'I connected with a motor I8, mounted on the adjacent side channel 2 of the base frame I.

The foregoing structure is old in the art. However, the present invention differs therefrom, in that substantially the entire weight of the screen frameIIl is supported upon the shaft 6 through the journal boxes 9 eccentrically mounted thereon, and to prevent tilting or rocking of the main frame I0 about the axis of the eccentrics 1, substantially non-resisting holders I9 are connected to the ends of the side angle irons II, and the transverse channels 3 of the base frame I, as best illustrated in Figure 1.

The holders I9 are constructed in the form of spring straps having an intermediate transverse bend 26 providing substantially vertical and horizontal stretches 2| and 22, respectively, of substantially equal length. The upper end of each arm 2I is offset at a right angle for attach ment to the under face of one of the angles II adjacent its end, while the end of the arm 22 is bent upwardly at a right angle for attachment to the adjacent transverse channel 3.

As previously explained, the entire weight of the screen frame is supported upon the shaft 6, and therefore the spring straps I9 are so designed as to offer substantially no resistance to the circular movement of the screen, and are merely vided as holders to prevent the screen from tilting about the shaft 6. With this in view, the tension of the arms 2| and 22 of the holders I9 is so gauged as to compensate for one another during the vertical circular movement of the screen frame, whereby the resultant resistance to the movement of the screen is reduced to a negligible factor. Incidental to the foregoing, it is further important that the resilient holders be positioned longitudinally with respect to the plane of movement of the screen frame, and while the preferred shape of holder has been illustrated and described in detail, it is to be understood that the same may be modified, and other shapes of holders produced for accomplishing the same results, it being merely necessary that the holders be of such design as to compensate for the circular movement of the screen frame to the extent of offering substantially no resistance to such movement.

From the foregoing explanation, consideredin connection with the accompanying drawings, it is believed that the operation and advantages of the present structure over previous types of screens will be quite apparent, in that, due to the fact that the vibrating screen is supported substantially entirely upon the shaft 6, it can be readily counter-balanced to the extent that no complicated forces are imposed upon the drive shaft or the frame, and after this is once accomplished, there is no adjustment or resetting required at any time.

Inasmuch as the end holders I9 are designed to offer substantially no resistance to the positive circular movement of the screen imparted by the eccentrics, there is no need to change the counter balance, as no force would come into play to upset the same. This reduces the cost of the screen, in that expensive counter-balances are not required, and furthermore the proper counterbalance is definitely determined by the simple method of computing the weight of the screen, and the eccentricity to determine the moment of the screen, thus eliminating trial and error methods, and the possibility of subsequently upsetting the adjustment, making the screen foolproof after it leaves the factory.

Since the drive shaft can be counter-balanced with great accuracy, the vibrating screen will not transmit any forces other than the dead load of its own weight to the base frame through the journal boxes 4. Neither will the end holders I9 transmit any forces to the base frame, since they are substantially non-resistant to the action of the screen.

Obviously, the foregoing structure requires a minimum amount of power for actuating the screen, since the necessity of compressing and overcoming the force of resilient supports used in other types of screens is eliminated.

Another important advantage, especially to the designer, results from the fact that the magnitude and direction of all of the forces exerted on the drive shaft are known, and no undeterminable forces of resilient supports need be considered, thus permitting the accurate determination of stresses at any point on the drive shaft, which eliminates guesswork.

Considering all of the advantages resulting from the present invention over previous types of screens, it will be appreciatedthat a highly efficient and comparatively inexpensive structure has been provided, which is practically fool-proof, requiring little or no maintenance in the field, other than those necessitated through ordinary wear, and which imparts practically no vibration to the supporting base, which ishighly desirable in instances where the screen is installed within a building. Further, the present invention permits of an exceedingly light construction, which not only reduces the cost of manufacture, but also effects a material reduction in the cost of operation.

I claim:

A vibrating screen comprising a base, a powerdriven eccentric shaft journaled on said base, a vibratory screen supported substantially entirely upon said eccentrics and actuated thereby, and

independent resilient straps connecting the ends of said screen with the ends of the base, said straps being positioned longitudinally with relation to the plane of movement of said screen, and

having an intermediate transverse bend to provide right angle arms of substantially equal length to render the strap non-resistant to the movement of said screen, the vertical arm being attached to said screen and the horizontal arm 5 being attached to said base.

PETER H. TOEPFER. 

